Ramp

I'm working my way through the grounds. Overall, just from the grounds, fuses and relays I've cleaned, various issues are clearing up. Tonight I decided to do the 14 Pin connector -good condition but cleaned it up and the jump terminal.
Then I moved to Ground MPIII. Then moved to MP X and this is what I found ! It looks cut to me !

I looked at the wiring diagrams to see what this ground is for but can't find it. Thoughts on how this may be affecting performance ?

docmirror

Yikes! That is the main ground from the chassis to the engine and is critical for operation. It does look cut. Replace, and drive on. Doing good work there.

Mrmerlin

thats a ground from the cam tower to the coil bracket bolt ,
if you make a ground wire use fine strand wire it will handle a lot of flexing before it breaks

Ramp

I'm going to see what the LAPS has as a replacement.

Why would someone cut this and wouldn't I have significant issues ?

merchauser

guessing that you are not experiencing issues because there are many grounds that are redundant
and so when one is removed is doesn't create a catastrophic situation

Adk46

I found this cable broken on my car, too (no running issues - I think there are two other big ground cables to the engine). Almost looked cut, but not cut - just failed in fatigue from all the engine movement/vibration. The factory cable is too short or is prone to be installed too taut. Stan's advice about using a fine-wire cable sounds good, but what I did was make it longer and attach it further way, with slack, to reduce the strain range imposed by engine movement.

Ramp

MP X is fixed, thanks. Now, can anyone identify this ground ? Its attached to the driver side wiper mount. It does not show on the ground diagram. Thoughts ?

Also, how do you get to MP II ??? (near pass side of radiator)

P.S. - ADK I love driving in your neck of the woods. My wife and I usually take a 2-3 day run in July/August through high mountain roads to Placid area with my '87 911. Great driving ! I'm jealous you have that in your backyard.

Landseer

Not all the grounds are represented in the diagram, and the diagram is year dependent.


the grounds on the two coil brackets and the one on the wiper motor are strictly for radio noise suppression. That reference is obscure, buried in tech notices that can be found deep in the special CD set.
The radio antenna amp also has a ground, it' location is way up under dash where windshield antenna leads enter car, above and requiring removal of glove box, not generally worth the effort.

Landseer

Grounds up front near radiator are awkward, on pre s4 I've been able to address with 10 mm gear, moving a bracket first.

Adk46

Very good, indeed, as Camp 928 attendees last year can attest. Route 73 is a real adventure during a blizzard. The ground point discussion might make for a good tech session for Camp 928 - June 15-17, 2018 next year. Come on up! See link below.

The ground points under the intake are considered a great challenge - have they come up yet? My car is generally non-crusty and I have never felt the need to go through all the ground points. I've cleaned them as I encounter them doing other things.

Ramp

ADK - I will make a note and see if I can make it up there that weekend.

I have not gotten to the bell housing grounds yet (under the air filter) - thought I would save those for last. The car is a 1 owner original with 40k but needs deferred maintenance and tlc. I decided to sort the electrical first and get everything functional before moving to the mechanical and bigger items. So far, doing the electrical - fuses, grounds, relays etc has made a marked improvement all around and giving me a bit more confidence in this car - my first 928

Alan

On S4+ cars MP II is in just front of the radiator (e.g. towards front of car) on the passenger side fender wall - under the fender lip.

Bend down low in front of radiator to see it. Not too bad to reach with a socket extension.

Alan

Alan

I think that is the wiper motor ground wire. The diagrams show this connected to GP IV - though that is inside the car behind the pod. I wonder if this is actually the same point on the other side of the firewall and therefore considered the same GP?

Alan

Landseer

Like other radio suppression GP s, likely not listed.

maybe someday we will post pre s4 ground point diags in faq thread.

outbackgeorgia

Looks loke a fatigue break, notice the failure at the end of the crimp. Possibly the wire was not secured properly and constant flexing over the years caused separation. Replace the wire and secure so it will not move.